Fusible link



Dec. 30, 1924 1,520,750

W. K. HODGMAN FUSIBLE LINK Filed Feb. 28, 1920 VE/V TOR. Mai/1 1a. f/n wkm,

Patented Dec. 30, 1924.

UNITED STATES PATENT OFFICE.

WILLIS K. HODGMAN, OF TAUNTON, MASSACHUSETTS; EMMA A. HODGMAN EXECU- TRIX OF \VILLIS K. I-IODGMAN, DECEASED.

FUSIBLE LINK.

Application filed February 28, 1920.

To all whom it may concern.

Be it known that I, VVILLIs K. HODGMAN,

a citizen of the United States, residing at Taunton, in the county of Bristol and State of Massachusetts, have invented new and useful Improvements in Fusible Links, of which the following is a specification. My invention relates to improvements in fusible links used in automatic sprinklers for extinguishing fires, or in other devices wherein it is desirable to hold certain parts of the mechanism to which they are applied in assembled condition until a predetermined degree of temperature exists in the vicinity of the apparatus and melts the solder uniting the parts of the links.

The objects of my invention are to provide a fusible link of superior efficiency as to both its holding and releasing functions.

I attain these objects, in a fusible link of the three piece type embodying the principle of the invention, by employing two opposed plates having relatively shoal trans verse channels, substantially rectangular in cross section, which provide a chamber between the plates which is occupied by a fulcrum-block located half and half in each of the plates; thus making a fusible link wherein the bearing surfaces of the fulcrumblock or of the channels, which take the tension normally set up in the link, may be formed so as not only to provide a certain and positive tilting tendency to the fulcrumblock but also to provide means whereby a part of the solder, uniting the parts of the link, being in compression and co-operating with the fulcrum-block will form a substantially solid strut in the plane of tension.

In order that the principle of the invention may be readily understood, I have disclosed a single type or embodiment thereof in the accompanying drawing, in which Figure 1 is a side elevation of my link; and Fig. 2, a vertical section on line 22, Fig. 1.

Similar numerals refer to similar parts throughout the several views.

My fusible link, as shown in the drawing, is of the three piece type and consists of the duplicate plates 4 and 5, the fulcrumblock 6 and a fusible solder which melts at a predetermined degree of heat. The solder is applied between the opposed sur- Serial No. 362,067.

faces of the parts of the link in the usual manner but is not shown in the drawing.

Each of the plates is provided, near its outer end, with an aperture 7 to receive one of the parts to be held in assembled condition, shown in the drawing as the end of one of the levers 8 or 9 (shown in Fig. 2, only) of a usual type of automatic sprinkler (not shown).

The inside face of each plate near its inner end is provided with a transverse channel 10, rectangular in section, and with sides perpendicular to the face of the plate.

The fulcrum-block 6 is of slightly less width over all than the width of each channel 10 10 thus being free to tilt and pry the plates at and 5 apart when the solder melts, and its edges are grooved or concaved as plainly shown in the drawing. The thickness of the fulcrum-block is twice the depth of each channel so it is normally located half and half in the channels. The

object of the concave edges of the fulcrum- Having described the releasing properties peculiar to my fusible link I will now proceed to describe its peculiar holding properties.

Referring to Fig. 2, attention is directed to the two spaces or chambers 11 11 formed because the two opposed channels are out of register or overlap at their ends. These chambers are located between the non-bean ing edges of the fulcrum-block 6 (by nonbearing edges, I mean the edges which do not have direct contact with the sides of the channels 10 10) and the inclosing walls of the channels 10 10. Normally the chambers 11 11 are solidly full of solder which not only neutralizes the effect of the off-set bearings of the edges of the fulcrum-block 6 with the bearin sides of the channels 10 10, previously described, but also provides a substantially solid strut directly in the plane indicated by the dotted line 09-50, because the operative position solder in the chambers 11 11 will, provided the fulcrum-block 6 attempts to tilt, be instantly placed intcompression. V

\Vhen the link is assembled the channels in the plates overlap and the fulcrum block is mounted in that portion of the chamber formed by the overlapped portions of the channels. The fulcrum block, it will be noted, is symmetrical with respect to a plane extending midway the thickness of the block. Hence the fulcrum block maybe placed in position with either grooved edge up or down and with either face against the bottom-of either channel. The fulcrum block is thus reversible both edgewise and endwise. This is of material advantage in assuring the correct assembly of the link because it is impossible by reason of this symmetrical form of the fulcrum block to place it in the wrong position.

The mass of solder which fills that portion of the chamber formed by the channels not occupied'by the 'fulcrumed block forms, as already noted with the block, a-solid strut which takes compression. The fusible solder nsedin these links is subject to cold flow under the strain imparted to the links by the levers 8 and 9 or similarelements but in the'case of this invention owing to the fact that the bearing edges of the block are seated against the adjacent opposed sides of the channels any tendency to cold flow cannot impair the holding quality of the link in the line or plane of the strain thus insuring that-the link shall retain its proper until the solder is melted or fused by heat. hen this takes place the action is apositive one and insures the quick separation of the linksso that they fall apart at once as required.

Having thus described oneillustrativeem- 'bodiment of my invention, I desire it'to be understood that although specific terms are employed, they are used in a generic and descriptive sense and not for purposes of formed by the channels ofthe plates "placed face to face.

'2. A fusible link comprising two plates each having a similar transverse channel substantially rectangular in .cross section withits bottom parallel to the face of the plate, the saidplates being assembled face to 1' face with the channels overlapping, a fulcrum block of substantially less width than the channels, of a thickness substantially equal to the combined depths of the channels, having vits edges grooved longitudinally, symmetrical with respect to a plane -midway.its thickness, and positioned in that portion of the chamber formedby the overlapped channels with two 1' of its diagonally opposite bearing edges engaging the -.ad'ja-" cent opposed sides ofthe channels, and fusible solder filling the space in the 0pposed channelsnot occupied-by the fulcrum .block and extending between and securing together :the faces .of the plates whereby when thesolder is cold a solid compression strut .is formed by the solder and the fulcrum block in the opposed channels ,and

when the solder is melted and the plates forced againstthe bearing edges ofthe ifulcrum block the plates are positively separated bythe rocking of :the :fulcrum block.

WILLIS K. ,HODGMAN. 

